1. Technical Field
The present invention relates generally to ion implantation, and more particularly, to in situ surface contaminant removal for ion implanting.
2. Related Art
Semiconductor wafers that are to be ion implanted typically have contaminant materials and oxides on the wafer surface. These materials can contaminate the implant process and cause dose non-uniformity and reduced dose retained in the silicon.
Conventional surface preparation procedures include pre-cleaning techniques that are external to an ion implantation chamber. One of these approaches includes stripping of native oxide from the wafer, and exposing the wafer to a high vacuum environment to allow water vapor to evaporate off of the wafer surface. Unfortunately, externally removing oxides still allows for oxide re-growth as the wafer is transported to the implant tool. Accordingly, the performance of devices on the wafer may be limited by the external environment in which they are cleaned. In addition, since the external environment is typically not controlled, the repeatability of the transport conditions also may affect performance.
In view of the foregoing, there is a need in the art for a way to prepare a wafer surface for ion implantation in situ.